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is very distinctly discernible, though the arteries can 

 scarcely be seen on account of the thickness of the shell 

 intervening. The number of strokes is as above men- 

 tioned when the shell is placed on the table, but we no 

 sooner take it into our hands, than its pulsation is in- 

 creased to an almost feverish rapidity, and we count 

 upward of 100 strokes per minute. This seems really 

 marvellous, and we immediately exclaim, " What can 

 be the cause of this ? it cannot arise from fear, it surely 

 must be the heat of the hand ; " so, in order to test the 

 the truth of this surmise, we prepare a cooling mixture, 

 and place our subject so that it may be affected by the 

 cold without being wetted. Our theory is verified, for 

 in a very few seconds their pulsations seem almost to 

 cease, or to go on so languidly as to make it difficult to 

 count the strokes ; probably they may not be more 

 than 20 per minute. But we soon perceive the benefit 

 that is to result from such a provision ; it is one of the 

 many evidences of design on the part of an all-wise 

 Creator, with which the animal kingdom abounds. 

 During the winter, mollusks hybernate, and remain for 

 several months in a state of torpor, without partaking 

 of any nourishment, as is evident, since they seal up 

 the entrance of their domain at the commencement 

 of severe weather, and do not come forth until the 

 warmth of spring calls them into more active existence. 

 How important, then, that as little waste as possible 

 should go on during that period ; and in no other way 

 could this be brought about so effectually as in having 

 the circulation decreased to such a degree as almost to 

 cease during the severity of the winter season. 



